1. Field of the Invention
The present invention relates to an information processing apparatus and an operation method of a storage system, and more particularly to a technique for properly managing differential volumes used to provide a snapshot function depending on the significance levels of individual data pieces and the like.
2. Related Art
Of the functions of a storage system, there is one (hereinafter referred to as a snapshot function) with which, for a volume in operation (hereinafter referred to as an operational volume), the state at a certain time (hereinafter, the state is called a snapshot) is provided to a user in response to a request from the user or the like. This snapshot function is generally implemented in such a way that data (hereinafter, called differential data) for reproducing the snapshot of a running volume at a certain time are saved in advance in a volume (hereinafter, called a differential volume) different from the operational volume, and that the snapshot at the certain time is reproduced using the present data of the operational volume and the differential data saved in the differential volume.
With this method, when the remaining amount of a differential volume is insufficient, differential data on a newly updated data cannot be managed. To address this problem, for example, Japanese Patent Application Laid-open Publication No. 2006-119688 describes a method in which a use rate of a differential volume and a threshold value are compared, and an update of differential data to the differential volume is controlled depending on whether or not the activity rate is beyond the threshold value.
Significance levels differ between individual data pieces used by a user of a storage system. Accordingly, when operating the storage system, it is preferable that a management method of differential volumes be flexibly set depending on individual data pieces in consideration of the activity states of storage resources usable as differential volumes.
Therefore, an object of the present invention is to provide an information processing apparatus and an operating method of a storage system which are capable of suitably managing differential volumes.